There are a great many fabric conditioners available for use in a home laundry. Generally, the known fabric conditioning agents can be grouped into the following classes which contain compounds having at least one long chain group:
(1) Cationic quaternary ammonium salts; PA1 (2) Nonionic compounds, such as tertiary amine oxides; PA1 (3) Anionic soaps, sulfates, and sulfonates; PA1 (4) Zwitterionic quaternary ammonium compounds; PA1 (5) Ampholytic tertiary ammonium compounds; and PA1 (6) Compatible mixtures of one or more compounds of these classes.
More specifically, with respect to the use of amine oxides in fabric conditioners,
U.S. Pat. No. 3,660,286 discloses a fabric softening composition comprising a mixture of a quaternary ammonium compound and an amine oxide. The quaternary ammonium compound has branched and straight chain higher alkyl groups in combination with lower alkyl groups. The amine oxide has one alkyl radical having from about 16 to 22 carbon atoms or the 2-hydroxy derivative thereof along with lower alkyl radicals. The combination of materials are said to provide fabric softening compositions which are useful in the liquid or solid state.
U.S. Pat. No. 3,892,669 discloses a clear homogeneous liquid aqueous fabric softener composition containing solubilized tetraalkyl quaternary ammonium salts having two short chain alkyl groups and two long chain alkyl groups together with solubilizers which can be anionic, nonionic, or amphoteric surfactants. The examples of the nonionic surfactants include tertiary amine oxides having one alkyl group ranging from C.sub.8 to C.sub.16 or the hydroxy-substituted alkyl groups.
U.S. Pat. No. 3,554,784 discloses fabric softeners in aqueous solution containing up to about 2 percent of a trialkylamine oxide with one of the alkyl groups having from 20 to 30 carbon atoms, a second alkyl group having from 1 to 20 carbon atoms, and wherein the third alkyl group contains from 1 to 3 carbon atoms. The preferred softening agents are trialkylamine oxides wherein one alkyl group contains from 20 to 26 carbon atoms, and the remaining two alkyl groups contain from 1 to 3 carbon atoms. All of the specific alkylamine oxides disclosed are the trialkylamine oxides wherein two of the alkyl groups are lower alkyl, and the remaining alkyl group is a higher alkyl having at least 20 carbon atoms.
U.S. Pat. No. 3,822,145 discloses fabric softeners comprising poly-lower alkylenes such as polyethylene. It is indicated that the fabric softeners can include amine oxides which are higher alkyl, di-lower alkyl amine oxides wherein the higher alkyl contains from 8 to 20 carbon atoms, preferably from 12 to 18 carbon atoms; and the lower di-alkyl group contains from 1 to 4 carbon atoms, preferably methyl.
U.S. Pat. No. 4,156,592 discloses an open-celled reticulated polyurethane foam compressed to form a sheet or wafer containing a fabric softener. The fabric softeners can include a tertiary amine oxide.
U.S. Pat. No. 4,242,377 discloses fabric conditioners wherein the fabric conditioner can include higher alkyl di-lower alkyl amine oxides wherein the higher alkyl contains from 8 to 20 carbon atoms and the lower alkyl contains from 1 to 4 carbon atoms, with the lower alkyls preferably being methyl.
None of the aforesaid patents discloses examples of fabric conditioners which utilize tertiary amine oxides having more than one higher alkyl chain, and the patents do not suggest that amine oxides having two higher alkyl chains will provide a beneficial result.
It is generally known in the art that fabric conditioners must impart softness, determined by the feel, to the conditioned fabric and, additionally, must have substantivity which means that something is there whether it feels good or not. Additionally, the fabric conditioner must have good dispersibility in water and impart antistatic characteristics to the conditioned fabrics. It is also recognized in the art that in formulating a fabric conditioner there is a degree of tradeoff in obtaining all of the aforesaid characteristics. Thus, it is known that if the carbon content of fabric conditioning components is increased from about C.sub.16 to C.sub.22, the softness imparted by the composition is increased. However, increasing the carbon content from 18 to 22 carbon atoms in an alkyl chain, while increasing the softness, decreases the water-dispersibility of the product and increases the water-repellency, leading to a waxy feel of the treated fabrics. Further, it is known that the C.sub.18 -C.sub.22 alkyl chains have a tendency to lower the substantivity of the composition. Although the substantivity can be enhanced in certain compositions by including a material having from C.sub.10 to C.sub.14 carbon atoms in the alkyl chain, the lower carbon content materials will detract from softness. Accordingly, in spite of the recognized characteristics of fabric conditioners, it is still difficult to provide a composition having all of the desired characteristics.